1. Field of the Invention
The present invention relates to a semiconductor device and its manufacturing method.
2. Description of Related Art
In general, a semiconductor device for sensing an external physical quantity (pressure, temperature, mass, etc.) should be so designed that the external physical quantity is intactly transmitted to a semiconductor die or a microelectromechanical system (MEMS) sensor and is simultaneously protected from external stresses. For this purpose, a MEMS sensor sensing an external physical quantity is usually coated with a very soft insulating gel, and all of the remaining regions, such as a semiconductor die, a substrate or the like, are encapsulated with a hard encapsulant. As the case may be, of course, a certain region of the insulating gel needs to be exposed to the exterior so that an external physical quantity can be intactly transmitted to the MEMS sensor through the encapsulant.
In such a case where the insulating gel needs to be exposed, the conventional encapsulating method has a problem in that the size and shape of the insulating gel exposed through the encapsulant becomes irregular due to the volume and the tolerance for height of the insulating gel.
Also, in order to perform an encapsulation process while an insulating gel is opened, a mold formed with a through hole may be used. However, forming the through hole in the mold itself is very difficult.
Furthermore, if the temperature of the semiconductor device falls to a normal temperature (25° C.) after the high-temperature encapsulation process, the insulating gel, which has been expanded by the temperature of mold (175° C.), shrinks its volume, so that height of the insulating gel is lowered to less height than that of the formed encapsulant. This phenomenon causes delamination between the insulating gel and the encapsulant, etc., thereby considerably deteriorating the reliability of the semiconductor device.